Hi,
I live in a 6 year old town-home. For the last 3 years or so water has been seeping underneath my kitchen cabinets and dishwasher in between the tiles only.

Please note, water does not leak from underneath the kitchen sink and I DO NOT use the dishwasher.
The seeping only happens at certain times. In the summer it happened for a few days and then went away. Now it is fall and it is back again.
It's just annoying. If I do not turn on the kitchen faucet there would be no water leak.

Is this a condensation problem with the pipes?

First, it does appear to be your kitchen causing this and not a unit above or below you.

Do the 2 water supply pipes to the faucet come up through the bottom of the cabinet, or in from the back wall?
Also does the drain go down through the floor of the cabinet, or back into the wall?
Is there a basement below you so that you can look for water dripping down any pipes directly under the kitchen?